AJR:178, May 2002 1063 nthrax is a bacterial infection that occurs when Bacillus anthracis en- dospores enter the body through abrasions in the skin, by ingestion, or by inhala- tion [1]. Inhalational anthrax, the most aggres- sive form, usually progresses unnoticed in the early stages with the resultant high mortality be- cause of the delay in diagnosis. Traditionally an occupational disease, inhalational anthrax has recently emerged as an agent for bioterrorist ac- tivity. In prior chest radiography reports about cases of inhalational anthrax, researchers de- scribed peribronchial infiltration, mediastinal widening, lymphadenopathy, and pleural effu- sions [2, 3]. In this report, we describe the find- ings on dynamic and delayed chest CT in a patient with advanced inhalational anthrax, which to the best of our knowledge has not yet been reported in the literature. Case Report A 61-year-old woman with a history of hy- pertension presented to the emergency depart- ment complaining of worsening shortness of breath, dyspnea at rest, and substernal pain that had begun 3 days earlier. Associated chills and cough productive of blood-tinged sputum were noted. Physical examination revealed an alert and oriented woman with a respiratory rate of 38 breaths per minute and a temperature of 36.0ºC. Diffuse bilateral rales were noted at chest auscultation. Blood tests revealed a WBC of 11.4 × 10 9 /L (normal range, 4.5–11.0 × 10 9 / L), lactate dehydrogenase of 1370 U/L (nor- mal range, 50–200 U/L), aspartate aminotrans- ferase of 240 U/L (normal range, 20–48 U/L), alanine aminotransferase of 263 U/L (normal range, 10–40 U/L), and a normal coagulation profile. A portable anteroposterior upright radiograph of the chest obtained shortly af- ter presentation revealed marked widening of the superior mediastinum. Bilateral peri- hilar opacities were present, and moderate pleural effusions with fluid in the minor fis- sure (Fig. 1A) were detected. Therapy for congestive heart failure was initiated; how- ever, several hours later, a bedside echocar- diogram showed a normal ejection fraction and wall motion with mild pericardial effu- sion. The patient was then given levofloxacin for atypical pneumonia. While in the emergency department, the pa- tient developed respiratory failure requiring me- chanical ventilation, placement of a pulmonary artery catheter, and transfer to the intensive care unit. A second portable anteroposterior supine chest radiograph obtained approximately 12 hr after presentation revealed further widening of the mediastinum. Marked hilar enlargement was visible. An exact size comparison of the pleural effusions on this chest radiograph with those on the earlier chest radiograph was diffi- cult because the patient’s position had changed, but the effusions appeared to have increased in size (Fig. 1B). Blood samples were collected for Gram staining and cultures. Contrast-enhanced CT was performed ap- proximately 16 hr after presentation to evaluate for possible anthrax infection and to rule out pulmonary embolism (Figs. 1C–1F). The CT scanner (CTi; General Electric Medical Sys- tems, Milwaukee, WI) was set at 140 kVp and 260 mA/sec with a 3-mm collimation and a pitch of 2.0, and CT was performed after the IV administration of 150 mL of IV contrast material (Omnipaque [iohexol] 300 mg I/mL; Nycomed, Princeton, NJ), which was injected at a rate of 3.5 mL/sec after a 25-sec delay. Additional CT im- ages of the entire chest were obtained with a col- limation of 7 mm (Figs. 1G and 1H) 20 min after the initial injection of contrast material. The ini- tial CT scan revealed large bilateral pleural effu- sions measuring 13 H. A small amount of high- density material, measuring 37 H, was visible in the dependent aspect of the right pleural space. A large amount of heterogeneous material was present in the mediastinum from the thoracic in- let to the level of the diaphragm. The material had density measurements ranging from 18 to Dynamic CT Features of Inhalational Anthrax Infection Christopher M. Krol 1 , Martin Uszynski 1 , Evan H. Dillon 1 , Mina Farhad 1 , Stephen C. Machnicki 1 , Bushra Mina 2 , Lewis M. Rothman 1 Received November 14, 2001; accepted after revision February 26, 2002. 1 Department of Diagnostic Radiology, Lenox Hill Hospital, 100 E. 77th St., New York, NY 10021. Address correspondence to C. M. Krol. 2 Department of Internal Medicine, Division of Critical Care Medicine, Lenox Hill Hospital, New York, NY 10021. AJR 2002;178:1063–1066 0361–803X/02/1785–1063 © American Roentgen Ray Society Case Report A Downloaded from www.ajronline.org by 2402:800:62f0:1c62:edfe:da6:5804:e7b4 on 07/14/23 from IP address 2402:800:62f0:1c62:edfe:da6:5804:e7b4. Copyright ARRS. For personal use only; all rights reserved
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